The exact in situ strain response of articular cartilage under physiological loading conditions has yet to be elucidated. An accurate understanding of these strains is essential in several respects, but most importantly, from a basic science perspective, knowledge of the normal mechanical function of cartilage can provide an explanation as to how cartilage can withstand the relatively harsh environment of diarthrodial joints. It is remarkable that, despite considerable work in the area of cartilage mechanics, the complete state of strain within contacting articular cartilage layers has not been reliably determined, and consequently the physiologic loading environment of chondrocytes has not been well characterized. To further elucidate these matrix load support mechanisms, measurements of twodimensional (2D) strains on the cross-section of articular layers are examined in the studies of this thesis. Methodologies for measuring these strains under relatively rapid loading rates are first developed and validated on bovine articular layers, then subsequently extended to the human patellofemoral joint.